1. Field of the Invention The present invention relates to a coil component, and particularly to a wire-connection structure of a surface-mount pulse transformer.
2. Description of Related Art
A pulse transformer is known as one of coil components. For example, the pulse transformer is provided in a connector that constitutes a connection point between a device, such as personal computer, and a LAN cable. The pulse transformer sends a pulse signal via the LAN cable. The pulse transformer serves to block ESD (Electro Static Discharge) or high voltage from entering and protect an internal circuit by an insulation between primary and secondary windings.
For example, Japanese Patent Application Laid-open No. 2010-109267 discloses a small surface-mount pulse transformer capable of high-density mounting. The pulse transformer includes a drum core, which has a winding core portion and a pair of flanges; and primary and secondary windings, Which are wound around the winding core portion of the drum core and each are equipped with a center tap. A first and a second terminal electrode, which connect both ends of the primary winding via a wire, and a third terminal electrode, which connects the center tap of the secondary winding with a wire, are provided in one of the flanges of the drum core. A fourth terminal electrode, which connects the center tap of the primary winding via a wire, and a fifth and a sixth terminal electrode, which connect both ends of the secondary winding with a wire, are provided in the other flange of the drum core. In this pulse transformer, two terminal electrodes that are connected with wires at the same timing are disposed in the same flange. Therefore, it is possible to reduce a winding work time at a time when an automatic winding machine that can perform wire-connection work only on one flange at one time is used to perform winding work.
In the conventional pulse transformer described above, the two ends of the primary winding wound around the winding core portion and the two ends of the secondary winding wound around the winding core portion are pulled out from the winding core portion and are connected via wires to corresponding terminal electrodes. In particular, the conventional pulse transformer has a wire-connection structure in which two lead wires that are pulled out from the winding core portion in a diagonally downward direction toward corresponding terminal electrodes cross each other. Accordingly, there is a possibility that the upper lead wire is pushed upward after coming in contact with the lower lead wire. A base portion of a wire-connection portion of the upper lead wire that is bonded in a thermo-compression manner to the terminal electrode may be subjected to an extra load due to the stress generated at that time.
Therefore, the object of the present invention is to provide a highly reliable coil component that can prevent an extra load being applied to a base portion of a wire-connection section in a wire-connection structure in which two wires that are wound around a winding core portion cross each other before being connected to corresponding terminal electrodes.